Hi, Charles,
Welcome to the forum. There are a lot of opinions on this topic, you can search a bit through Traveling to and from the Camino section and get some ideas. Are you buying a round trip ticket back to New York, or just a one way? If you are going round trip, I think it's worth considering both ways as you decide which airport to go into. If you're planning to end in Santiago, it is a whole lot easier to go Santiago to Madrid rather than Santiago to Paris. And Madrid to Saint Jean is pretty easy too. But some people want to spend time in Paris, so of course that means that it's not just a question about what's easier.
If you're going round trip, I would check out these multi-city options (multi-city is a feature in all advanced searches if you've never done it):
NY-Paris and Santiago-NY
NY-Pamplona and Santiago - NY
I always find that flying home from Santiago is never much more expensive than flying home from Madrid, and it saves a lot of time, if that's an issue, and usually some money as well, because the cost of the train to Madrid, plus maybe a night in a hotel, is usually more than the difference in airfare. Of course, you may want to spend time in Madrid so that wouldn't be the only consideration.
Buen camino, and happy planning! Laurie
